Due to the complex nature of the mammalian auditory systems it is often difficult to study many aspects of audition in these species. Consequently, various investigations have dealt with using lower vertebrates as 'model' systems for understanding homologous, but more complex, mammalian systems. One of the systems that may provide important insight due to its relative simplicity and accessibility is that in teleost fish. However, before this system can be used to answer many questions, it is necessary to obtain basic data on the function and capabilities of the system. In addition to overall analysis of auditory capabilities, data are needed on the function of specific sections of the teleost auditory system. Consequently investigations will be conducted on the peripheral auditory system of fishes. The studies will be directed towards a general analysis of the peripheral system as well as more detailed analyses of the roles of the specific structures in sound processing. Physiological, behavioral, and biophysical techniques will be used. Specific questions will relate to (a) processing of sound by the swim bladder, (b) the role of the swim bladder as a detector in different species, (c) the filtering characteristics of the Weberian ossicles, (d) the mechanisms of hair cell stimulation by the otoliths, and (e) the respone of the auditory nerve to sound stimulation.